/*	$OpenBSD: unexpand.c,v 1.13 2016/10/11 16:22:15 millert Exp $	*/
/*	$NetBSD: unexpand.c,v 1.5 1994/12/24 17:08:05 cgd Exp $	*/

/*-
 * Copyright (c) 1980, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * unexpand - put tabs into a file replacing blanks
 */
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "compat.h"

char genbuf[BUFSIZ];
char linebuf[BUFSIZ];

void tabify(bool);

int main(int argc, char *argv[]) {
  setprogname(argv[0]);
  bool all = false;
  char *cp;

  argc--, argv++;
  if (argc > 0 && argv[0][0] == '-') {
    if (strcmp(argv[0], "-a") != 0) {
      fprintf(stderr, "usage: unexpand [-a] [file ...]\n");
      exit(1);
    }
    all = true;
    argc--, argv++;
  }
  do {
    if (argc > 0) {
      if (freopen(argv[0], "r", stdin) == NULL) {
        perror(argv[0]);
        exit(1);
      }
      argc--, argv++;
    }
    while (fgets(genbuf, BUFSIZ, stdin) != NULL) {
      for (cp = linebuf; *cp; cp++) continue;
      if (cp > linebuf) cp[-1] = 0;
      tabify(all);
      printf("%s", linebuf);
    }
  } while (argc > 0);
  exit(0);
}

void tabify(bool all) {
  char *cp, *dp;
  int dcol;
  int ocol;
  size_t len;

  ocol = 0;
  dcol = 0;
  cp = genbuf;
  dp = linebuf;
  len = sizeof linebuf;

  for (;;) {
    switch (*cp) {
      case ' ':
        dcol++;
        break;

      case '\t':
        dcol += 8;
        dcol &= ~07;
        break;

      default:
        while (((ocol + 8) & ~07) <= dcol) {
          if (ocol + 1 == dcol) break;
          if (len > 1) {
            *dp++ = '\t';
            len--;
          }
          ocol += 8;
          ocol &= ~07;
        }
        while (ocol < dcol) {
          if (len > 1) {
            *dp++ = ' ';
            len--;
          }
          ocol++;
        }
        if (*cp == '\0' || !all) {
          strlcpy(dp, cp, len);
          return;
        }
        *dp++ = *cp;
        len--;
        ocol++;
        dcol++;
    }
    cp++;
  }
}
